I got the impression that BJ (Ivey's character) was written mainly to better serve the other characters' needs rather than written as a free-standing, well-drawn character. It was as if they decided Julia, Anthony and Mary Jo were "large enough" characters to be the main draw, while Carlene and BJ were just along for the ride, providing plot devices and witty remarks but not being given their own voices...basically how Anthony started out, and how Bernice remained through the series.
I've never viewed B.J. (Judith Ivey) in that light, but it does make sense. She was primarily written in to poke fun at Julia and bring forth some sass, but I'd say she was given some better thought than Allison (Julia Duffy) was given the year prior. B.J. is a likeable millionairess, and I like what Judith Ivey brought to really limited, one-note character. The episode "Love Letters", the one where she goes to her dead husband's vault, is quite lovely. She showed such sympathy and true love for a man that she had barely known.
Likewise, I can agree that, by that seventh and what they knew would be the final season, the writers and producers were more than willing to coast along the audience likability of Dixie Carter, Annie Potts, and Meshach Taylor. Alice Ghostley was an added bonus (they used her more than ever that final season), but Jan Hooks and Judith Ivey just seemed to be shuffled into the mix. I think a lot of that blame falls on the ever-declining writing, and the fault of the producers to be little effort into drawing stronger back-stories for Carlene and B.J. The writing was on the wall that seventh year, but even so, I think had CBS kept the show on Monday nights, it might would've came back for one more year.
Perhaps you're right, but I felt quite the opposite. Anyone they brought in would be spoken of as "replacing" Delta Burke, no matter how different the character might be. Being "the replacement" when most people didn't want one creates a certain amount of resistance in the viewers' minds before the new actress even hits the stage. Hiring Julia Duffy (beloved for her role on Newhart) was probably seen as a good way of getting past that resentment, since people who liked Stephanie (her role on Newhart) would give her more of a chance. But the viewers might have been put off by Alison not possessing some of Stephanie's better qualities, and of course the effort to establish her as a thorn in Julia's side was not balanced by the sort of vulnerable charming-ness we saw in Stephanie. The producers should have given Alison at least one character (Anthony would have probably been best) to let down her guard with, someone she could interact with on a more sympathetic level and allow her to show she wasn't totally chilly and remote....and someone who could work both sides of the fence from the start to help ease her into the ensemble.
I've always felt that Julia Duffy and her agents felt it was a good move for her to join DESIGNING WOMEN, giving all the publicity hoopla surrounding Delta Burke's exit.
I recall an interview with Linda Bloodworth-Thomason where she said that Julia Duffy was a well-liked actress, and that she was very capable of playing those "love to hate" kind of characters. There was a lot of hype for her coming in apparently, naturally riding off the publicity she had generated with her NEWHART role, which she had played for seven or eight years.
As it has been said, Julia Duffy was given no favors when it came to the writing. Her character, Allison, was not given any redeeming qualities, which was very unlike her former role, Stephanie, and Suzanne (Delta Burke) inside the DESIGNING WOMEN universe. She was all brass, and they wrote her into a corner with her Obnoxious Personality Disorder. Still, I find myself rooting for her, and always hoping that somewhere the writers were wanting to make her "work" and stay with the show. Had Allison and Anthony confided in one another (in a similar way Suzanne and Anthony had done), then Allison could have eased her way into the clique. Anthony could have eased her into the rest of the crew, and Allison could have been in the circle a few episodes into the season.